1. Field of the Invention
The present invention relates to a device for the diagnosis of vulnerable plaque in blood vessels.
2. Description of the Prior Art
Vulnerable plaque rupture is believed to be the cause of death in a large percentage of patients suffering heart attack and stroke. Detection of vulnerable plaque is problematic because the vulnerable plaque may not be associated with arterial blockage or the like. Arterial blockage detection generally relies on radiographic techniques.
Accordingly, there exists a need for an apparatus and related techniques for diagnosing vulnerable plaque in blood vessels. The present invention satisfies these needs and provides further related advantages.
The present invention may be embodied in device for detecting vulnerable plaque in a vessel by measuring the temperature of the vessel""s inner wall. The device may be a guide wire having a tube, an inner wire assembly, and a temperature sensor assembly. The tube has a lumen within the tube, a distal end with an opening into the lumen, and an external surface of a relatively constant radius from a generally central axis through the tube. The inner wire assembly may be located within and slide along the lumen. The inner wire assembly has a distal end that may be extended through the opening in the distal end of the tube. The temperature sensor assembly has a plurality of temperature sensors and a plurality of resilient arcuate delivery wires. Each delivery wire has a proximal end and a distal end. Each delivery wire""s distal end is attached to the inner wire assembly at a first location near the inner wire assembly""s distal end and each delivery wire""s proximal end is attached to the inner wire assembly at a second location spaced apart from first location in a direction away from the inner wire assembly""s distal end. The arcuate delivery wire forms a peak. A distance between the peak and the central axis is generally equal to or greater than the radius of the tube""s external surface. One of the plurality of temperature sensors is located near the peak of each arcuate delivery wire. When the temperature sensor assembly is located within the lumen, the resilient arcuate delivery wires are deformed to fit within the lumen. When the inner wire assembly is located with respect to the tube such that the temperature sensor assembly is extended beyond the opening, the arcuate delivery wires form the peaks for placing the temperature sensors in contact with the vessel""s inner wall for sensing the temperature of the vessel""s inner wall.
In more detailed features of the invention, the tube may include a guide-wire coil at the tube""s distal end. The resilient arcuate delivery wires may contact the vessel""s inner wall with a force of less than about 1.00 pounds per square inch and may be preformed of nitinol. Each delivery wire""s distal end may be fixed to the inner wire assembly at the first location and the delivery wire""s proximal end may be fixed to the inner wire assembly at the second location. Alternatively, the delivery wire""s proximal end may be attached to the wire assembly by being fixed to a sliding ring that may slide along the wire assembly as the delivery wires are deformed to fit within the lumen.
In other more detailed features of the inventions, the temperature sensors may be thermo-sensing contact junctions. Also, the plurality of sensing elements may comprise at least four sensors. The tube may include an end valve at the tube""s distal end for sealing the opening when the sensor assembly is within the lumen and is not extended through the opening. Alternatively, the distal end of the wire assembly may include a cap for covering the opening when the sensor assembly is within the lumen and is not extended through the opening. The inner wire assembly may include a wire having channels for forming feed-through lumens, when the inner wire assembly is placed within the tube""s lumen, for signal wires coupled to the temperature sensors.